Riveting gun



@cfh 23,, 134. E, w; STEVENS RIVETING GUN Filed Oct. 31, 1929 ATTORNEY.

range simple, compact and easily operated manthe escape of motive fluid.Still another object 'varied at will from a light tap for setting arivet Patented Oct. 23, 1934 PATENT oFFics RIVETING GUN Edward W.Stevens, Detroit, Mich., assignor to Chicago Pneumatic Tool Company, NewYork, N. Y., a corporation of New Jersey Application October 31, 1929,Serial No. 403,694

14 Claims. (01. 121-21) This invention relates to fluid pressure permcussive tools and in particular to single acting riveting hammers orguns adapted to head a rivet with one blow. Such tools are for use indriving small rivets as in aircraft construction work and similaroperations. 1

One object of the invention is to provide an improved tool of simple andstrong design and which is positive in action. Another object is to varyat will the force of the blow and to arual means for so doing. Anotherobject is to provide a novel throttle and exhaust control arrangement.Still another object is to utilize the die, rivet set, or other workingtool, to prevent is to retard the initial movement of the impact memberto insure ample volume of pressure fluid behind the same. Still .anotherobjectinvolves automatic means for restoring the impact member toposition for striking another blow. Other Objects will be apparent fromthe detailed description which follows.

The invention involves a pneumatic tool striking one blow at a time,which blow may be to a powerful smashing stroke which expands, heads,and clinches a rivet in a single operation. Releasable holding means forthe piston at the beginning of its stroke permits nicety of control ofthe force of the blow and preferably takes the form of a vacuum grip.The same holding means may form a cushion stop for the piston on itsback stroke. A single manually operated member governs the exhaust forthe opposite ends of the piston chamber as well as the admission of themotive fluid. The inletpipe for the motive fluid supply. may serve as astop for the control member. The piston is automatically returned forthe next blow by fluid pressure -means and the working tool is utilizedto prevent.

ing drawing, in which:

Fig. 1 is a longitudinal sectional view substantially on the broken linell of Fig. 3, showing a tool embodying the invention ready for use;

Fig. 2 is a sectional View similar to Fig. 1 show- "ing the tool at themoment of striking the blow;

Fig. 3 is a transverse sectional view substantially on the line 33 ofFig. 2; and

Fig. 4 is an enlarged detail sectional view show- .ing a modification.

The embodiment ofthe invention chosen, for the purpose of illustration,comprises a riveting gun having a cylinder 5 providing a piston chamberin which reciprocates hammer piston 6 to strike blows upon a workingtool such as a rivet set 7 slidably supported in a front head 8 which isthreaded into the forward end of cylinder 5 and serves both as a guideand a retainer for the working tool. To this end working tool 7 has astop collar or flange 7a which on outward movement engages a seat 8a onfront head 8 after the manner of a poppet valve for a purpose presentlyto be described. On its inward movement stop' collar 7a engages retainerring 9 for piston 6, which ring is clamped against a shoulder incylinder 5, by front head 8 and defines the front end of the pistonchamber. 1

By preference, and as a manufacturing expedient, cylinder 5 may beformed by inner and outer. sleeves 5b and 5a, respectively, having apress fit with each other and maintained in assembled relation by anysuitable means as by welding. Sleeves 5a and 5?) form therebetween anair chamber 10 which communicates with the forward end of the pistonchamber by a series, of ports ll in sleeve 5b and at its other end hasa'transverse series of exhaust ports 12 through the outer sleeve 50.. Inspaced relation to ports 12 is another transverse series of exhaustports 13 which extend through both sleeves of cylinder 5 and communicatewith the rear end of the piston chamber which is defined by a throttlehead 14 having a flange abutting the end of inner sleeve 51) and athimble like hollow projection 14a extending axially within the pistonchamber to cooperate with recess 6a inthe rearward end of piston 6 for apurpose presently to be described.

Slidably mounted within projecting portion 14a of the throttle head andcontrolling a series of inwardlyinclined inlet ports 15 substantially inthe plane of exhaust ports 13, is a throttle valve 16 having arestricted port 17 therethrough, to equalize the pressure on theopposite sides thereof. Valve16 is continuously forced outward by a coilspring 18 disposed ina recessed portion of the valve. Throttle valve16may be moved inwardly to open position by a stem or push rod 19 havingone end seated in a recess in the valve andthe other end guided by abore 20 in back head 21, the latter being threaded into the projectingend of outer sleeve 5a of the cylinder and acting through suitablespacing means, such asspring 22, upon throttle head 14. to maintain thelatter. in place.

i The control means for throttle valve 16 and for cylinder exhaust ports12 and 13 comprises a push handle 23 having a closed end to engage rod19 and a cylindrical portion 23a which is sleeved over cylinder 5 andprovided with a single transverse series of exhaust ports 24 arranged toregister with ports 13 when in its rearward position (Fig. 1) and withports 12 when in its forward position (Fig. 2). The motive fluid supplypipe 25 extends through handle 23, through bore 26 in cylinder sleeve 5aand has threaded engagement with a bore 21a in back head 21 therebyserving as a lock to secure and maintain the handle and associated partsin the rear end of the gun in assembled relation. Inlet pipe 25 alsoserves as a stop for the rearward movement of control handle 23 (Fig. 1)which is efiected automatically through the action of a coil spring 2'7seated against throttle head 14 on the one hand and a cup member 28engaging collar 19a on rod 19.

When handle 23 is in its rearward position (Fig. 1) piston 6 is alwaysreturned to and maintained at the limit of its rearward stroke inposition for the next blow by pressure fluid passing in limited amountthrough a constantly open port 29 in the flange of throttle head 14,which port communicates through a restricted port in a plug 30 with apassage 31 communicating with annular chamber 10 and thence throughports 11 with the front end of the piston chamber. The pressure fluidthus supplied acts on working tool 7 forcing it outwardly so that stopflange 7a acts as a poppet valve against seat 8a to seal the front endof the piston chamber. Exhaust ports 12 are sealed by sleeve portion 23aof the handle so that there is no escape for the pressure fluid. Recess6a and piston 6 make a sliding fit with projection 14a but there is justsufficient clearance to permit a slow outward or inward movement of airso that an air cushion is provided for the rearward movement of thepiston, thereby preventing breakage. The constant pressure applied bythe motive fluid in the forward end of the piston chamber graduallyforces out the air trapped between the head of piston 6 and the end ofprojection 14a so that piston 6 comes to rest normally in the positionshown in Fig. 1. The rearward edge of piston 6 is inwardly tapered at62) to assist in the escape of trapped air from recess 6a. This taperededge also provides clearance for the fillet at the base of projection14a and permits motive fluid issuing from ports 15 to circulate aroundthe end of piston 6.

When the operator uses the tool he directs working tool 7 to the workand as he applies pressure he forces tool 7 inwardly until flange 7aengages retainer ring 9. Control handle 23 is then forced forwardlybringing ports 24 and 12 into register, thus opening the front end ofthepiston chamber to exhaust. At the same time throttle valve 16 ismoved to the position shown in Fig. 2 admitting motive fluid throughinlet ports 15 against the inwardly tapered edge 61) of piston 6. Ifthrottle valve 16 is opened slowly, the small amount of motive fluidthus admitted moves piston 6 gradually away from projection 14a and thepiston strikes a light blow or tap upon tool 7 to set the rivet. Onrelease of the handle, throttle valve 16 closes and exhaust ports 24 and13 are brought into register relieving the pressure in the rear end ofthe piston chamber (Fig. l) at the same time permitting the motive fluidflowing through passages 29 and plug 30 and passages 31 to build up andbecome effective to move piston 6 back for the next blow. The operatorthen forces handle 23 sharply forward until the handle strikes back head21. The large volume of motive fluid suddenly striking piston 6 tends tomove it quickly forward. This produces a suction hold within recess 6awith the result that a strong suction hold is effective upon piston 6.This retards the movement of the piston and permits air in full volumeto enter the rear end of the piston chamber so that when the suctionhold is finally released the piston 6 shoots forward and delivers apowerful smashing blow which expands, heads, and clinches the rivet.

Fig. 4 shows a slight modification of the control arrangement wherebymotive fluid passes into chamber 10 for the back stroke of piston 6 onlywhen control handle 23 is in its rearward position. To accomplish thisthe port through the flange of throttle head 14 is omitted and in placethereof spaced ports 32 and 33 are provided in outer cylinder casing 5a,which ports are bridged by a groove 34 in handle sleeve 23a. Plug 30a,with its restricted port, establishes communication between port 32 andpassage 31.

While the invention has been herein described in what is now consideredto be a preferred embodiment, it is to be understood that the invention1 is not restricted to the specific details thereof but covers allchanges, modifications, and adaptations within the scope of the appendedclaims.

I claim as my invention:

1. A fluid pressure percussive tool having a pis- 1 ton chamber, apiston reciprocable therein having a recess in its rearward end, aretarding device for the piston comprising a projection within saidcylinder conforming to said recess and making a sliding fit with saidpiston, thereby to 1 provide both a cushion stop and a suction hold forsaid piston, means for exhausting the pressure fluid from said recess,and manually controlled fluid pressure means for breaking said suctionhold. 1

2. A fluid pressure percussive tool having a piston chamber, a pistonreciprocable therein having a recess in its rearward end, a projectionwithin said cylinder conforming to said recess and making a sliding fitwith said piston, means for 1 simultaneously moving said piston intonested engagement with the projection and exhausting the air within saidrecess, thereby to provide a suction hold for said piston, and means insaid projection for admitting motive fluid behind said 1 piston when thelatter engages said projection.

3. A fluid pressure percussive tool having a piston chamber, a pistonreciprocable therein having a recess in its rearward end, a projectionwithin said cylinder conforming to said recess 1 and making a slidingfit with said piston, said projection having ports for admitting motivefluid behind said piston when the latter closely engages saidprojection, and a valve movably supported by said projection forcontrolling said 1 ports.

4. A fluid pressure tool having a cylinder, a piston reciprocabletherein, a throttle head within said cylinder defining one end of thepiston chamber, a throttle valve in said head, a back head for 1 saidcylinder in spaced relation to said throttle head, said spaced headsforming therebetween a chamber for pressure fluid, a control handlehaving a grip portion and a portion sleeved over said cylinder, apressure fluid conduit extending 1 through said grip portion of saidhandle and secured to said back head, and means whereby movement of saidhandle on said cylinder operates said throttle valve, said conduitserving as a stop for such movement. 1

5. A fluid pressure percussive tool having a piston chamber, a pistonreciprocable therein having a recess in its rearward end, a projectionwithin said cylinder conforming to said recess and making a sliding fitwith said piston, means within said projection for supplying motivefluid to said piston chamber to drive said piston away from saidprojection, and means acting automatically to restore said piston totelescoping relation with said projection when said first-named means isinoperative.

6. A fluid pressure percussive tool having a piston chamber, a pistonreciprocable therein having a recess in its rearward end, a hollowmember having a portion projecting within said cylinder and conformingto said piston recess so that said piston may telescope thereover with aslight clearance, said projecting portion having ports therethrough toadmit motive fluid behind said piston, and a manually operablevalveslidably mounted within said hollow member for controlling said ports.

'7. A fluid pressure percussive tool having a piston chamber, a pistonreciprocable therein having a recess in its rearward end, a projectionwithin said cylinder conforming to said recess and making a sliding fitwith said piston, said projection having ports for admitting motivefluid behind said piston when the latter closely engages saidprojection, a valve movably supported by said projection for controllingsaid ports, and means operating automatically when said valve is inport-closing position to restore said piston to telescoping relationwith said projection.

8. A fluid pressure percussive tool having a piston chamber, a pistonreciprocable therein having a recess in its rearward end, a projectionwithin said cylinder conforming to said recess and making a sliding fitwith said piston, said projection having ports for admitting motivefluid behind said piston when the latter closely engages saidprojection, a valve movably supported by said projection for controllingsaid ports, and means independent of control by said valve for admittingmotive fluid to the opposite end of said piston chamber to restore saidpiston to telescoping relation with said projection.

9. A fluid pressure percussive tool having a piston chamber, a pistonreciprocable therein having a recess in its rearward end, a hollowmember having a portion projecting within said cylinder and conformingto said piston recess so that said piston may telescope thereover with aslight clearance, said projecting portion having ports therethrough toadmitmotive fluid behind said piston, a manually operable valve slidablymounted within said hollow member for controlling said ports, and meanssupplying motive fluid in restricted amount to the opposite end of thepiston chamber to return said piston when said valve is in position toclose said ports.

10. A fluid pressure percussive tool comprising inner and outer sleevesforming a cylinder, said inner sleeve providing a piston chamber andsaid outer sleeve extending beyond said inner sleeve at one end, a headwithin said outer sleeve in engagement with the end of said innersleeve, a back head secured in the free end of said outer sleeve, andresilient means engaging said heads for yieldingly maintaining saidfirst head in place.

11. A fluid pressure percussive tool comprising inner and outer sleevesforming a cylinder, said inner sleeve providing a piston chamber andsaid outer sleeve extending beyond said inner sleeve at one end, a headwithin said outer sleeve in engagement with the end of said innersleeve, a back head secured in the free end of said outer sleeve,spacing means between said heads, means for controlling admission ofmotive fluid to one end of said piston chamber comprising a throttlevalve supported by said first-named head, and an operating member forsaid valve extending through said back head. i

12. A one-shot fluid pressure percussive tool 100 having a pistonchamber, a piston reciprocable therein, means for admitting pressurefluid behind said piston, means at the rear end of said chamber forsubjecting said piston to a suction hold to retard initial movement ofthe piston, said means comprising interfitting cylindrical parts on thepiston and the rear end of the chamber respectively, and means forholding the piston at said end of the chamber over a continuous period.

13. A fluid pressure tool comprising a cylinder having a piston chambertherein, a piston reciprocable in said chamber, a combined cushion andretarding device interposed between the rear ends of the piston andchamber respectively, one of said last-mentioned parts having acylindrical recess adapted to receive a close fitting projection on theother of said parts, said recess being adapted to cushion the piston atthe end of the rear stroke thereof, means for urging said pistonrearwardly for a sufficient length of time to exhaust air or pressurefluid from said recess, whereby a vacuum is subsequently formed in saidrecess when the piston is forced forwardly,'and means for admittingpressure fluid behind the piston to force the same forwardly, saidpressure fluid being adapted first to oppose the suction in the recessand then break the suction hold.

EDWARD W. STEVENS.

